A Novel Sandwich-Structured Phase Change Composite with Efficient Photothermal Conversion and Electromagnetic Interference Shielding Interface

Abstract

Stability and multifunctionality greatly extend the applications of phase change materials (PCMs) for thermal storage and management. Herein, CuS and Fe₃O₄ nanoparticles were successfully loaded onto cotton-derived carbon to develop a multifunctional interface with efficient photothermal conversion and electromagnetic interference (EMI) shielding properties. 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol (DMDBS) and expanded graphite (EG) formed an organic/inorganic three-dimensional network framework to encapsulate 1-octadecanol (OD) by self-assembly. Finally, multifunctional shape-stabilized PCMs (SSPCMs) with the sandwich structure were prepared by the hot-press process. Multifunctional SSPCMs with high load OD (91%) had favorable thermal storage density (200.6 J/g), thermal stability, and a relatively wider available temperature range with improved thermal conductivity to support the thermal storage and management realization. Furthermore, due to the synergistic enhancement of two nanoparticles and the construction of the carbon network with cotton carbon and EG, highly efficient photothermal conversion (94.4%) and EMI shielding (68.9 dB average, X-band) performance were achieved at about 3 mm thickness, which provided the possibility of the multifunctional integration of PCMs. Conclusively, this study provides new insights towards integrating solar energy utilization with the comprehensive protection of related electronics.

Keywords: electromagnetic interference shielding; multifunctional interfaces; organic composite phase change materials; photothermal conversion; thermal energy storage.

Figure 1

Schematic preparation of (a) C/CuS/Fe₃O₄ interface and (b) C-OD/DMDBS/EG composites.

Figure 2

(a) XRD patterns and (b,c) FTIR spectra of C/CuS/Fe₃O₄, C-OD/DMDBS/EG, and individual components.

Figure 3

SEM micrographs of (a,b) cotton yarn and (d,e) cotton-derived carbon; EDX and elemental distribution images of (c) cotton yarn and (f) cotton-derived carbon.

Figure 4

SEM micrographs for (a,c,d,e) C/CuS/Fe₃O₄ interface, (g) EG, (h) OD/DMDBS/EG composites, and xerogel of (i) OD/3%DMDBS/6%EG and (j) OD/1%DMDBS/6%EG; elemental mapping images of (b,f) C/CuS/Fe₃O₄ interface.

Figure 5

(a) TEM micrograph of CuS/Fe₃O₄ nanoparticles; corresponding (b) element mapping and (c) HRTEM images.

Figure 6

DSC (a) melting curves, (b) crystallization curves, and (c) enthalpies of phase transitions for various samples; (d) DSC cycling results for C-OD/3%DMDBS/6%EG.

Figure 7

(a,b) TG-DTG curves of OD, DMDBS, OD/6%EG, and C-OD/3%DMDBS/6%EG; (c) digital photographs of OD, C-OD/1%DMDBS/6%EG, C-OD/3%DMDBS/6%EG, C-OD/5%DMDBS/6%EG, C-OD/7%DMDBS/6%EG, and C-OD/9%EG heated for 60 min to 80 °C; (d) the relative remaining mass of the different samples; (e) thermal diffusivity and thermal conductivity of OD, OD/3%DMDBS, OD/3%DMDBS/6%EG, and C-OD/DMDBS/EG.

Figure 8

Infrared thermal maps of C-OD/3% DMDBS/6% EG, C-OD/6% EG, and pure OD upon heating and cooling at heating temperatures of (a) 65.8 °C and (b) 52.9 °C.

Figure 9

(a) UV-VIS-NIR absorbance spectrum of C-OD/3%DMDBS/6%EG and components; (b) temperature profiles under illumination of OD, OD/3%DMDBS/6%EG, and C-OD/3%DMDBS/6%EG; (c) temperature profiles of C-OD/3%DMDBS/6%EG at 7 complete cycles; (d) temperature profiles under illumination and (e) EMI SE_T of C-OD/3%DMDBS/6%EG after 72 h solar irradiation or 2 h soaking in water.

Figure 10

The EMI SE of (a) OD, (b) OD/3%DMDBS/6%EG, (c) C-OD/3%DMDBS/6%EG; (d) SE_T, SE_R, and SE_A of different samples at a frequency of 10 GHz; (e) SE_T of C-OD/3%DMDBS/6%EG with different thickness; (f) SE_T, SE_R, and SE_A of C-OD/3%DMDBS/6%EG with different thickness at a frequency of 10 GHz.

Figure 11

Digital photographs of Tesla kit experiment for (a) pure OD, (b) OD/3%DMDBS/6%EG, and (c) C-OD/3%DMDBS/6%EG; (d) the illustration of photothermal conversion and EMI shielding mechanisms.